3408E and 3412E Industrial Engines Caterpillar

Probable Causes

• Cold Mode

• Throttle position sensor

• Direct Fuel Control

• Injection actuation pressure

• Electrical connectors

• Unit injectors

• Fuel supply

• Air inlet and exhaust system

Recommended Actions

Note: If the symptom only occurs under certain operating conditions (high idle, full load, engine operating temperature, etc), test the engine under those conditions. Troubleshooting the symptom under other conditions can give misleading results.

Cold Mode

Use the Caterpillar Electronic Technician (ET) to verify that the engine has exited Cold Mode. Cold Mode operation may cause the engine to run rough and engine power may be limited.

Throttle Position Sensor

Monitor the status of the throttle position on ET. Verify that the throttle position sensor is operating correctly. Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for the proper troubleshooting procedure.

Direct Fuel Control

Monitor the status of the throttle position on ET. Verify that the direct fuel control is operating correctly. Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for the proper troubleshooting procedure.

Injection Actuation Pressure

1. Check the engine oil level. Engine oil supplies the injection actuation pressure circuit. The engine oil must be kept at the proper level for fuel injection.

   Note: If the oil has been drained from the unit injector hydraulic pump, the pump must be primed. Refer to Disassembly and Assembly, "Unit Injector Hydraulic Pump - Install" for the correct procedure.

2. If service has recently been performed on the engine, air may be present in the injection actuation pressure circuit. Allow the engine to fully warm up and operate the engine under load in order to purge the air from the injection actuation pressure circuit.

3. Use ET to check for diagnostic codes. If there is an Active Diagnostic Code for Injection Actuation Pressure, refer to the appropriate topic in Troubleshooting with a Diagnostic Code in this manual.

4. Compare the actual actuation pressure and the desired actuation pressure on the ET Status screen. If these readings agree within 2000 kPa (290 psi) during the symptom, the problem is not in the injection actuation pressure circuit.

5. Check the seals on the injection actuation pressure control valve. If the seals are faulty, replace the seals and repeat Step 4.

6. Check the wiring harness to the injection actuation pressure control valve for opens and/or shorts.

7. Measure the coil resistance on the injection actuation pressure control valve. If the coil resistance is not within 10 ± 5 Ohms, replace the injection actuation pressure control valve.

Show/hide table

Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

8. Use ET to perform the Injection Actuation Pressure Override Test. If the injection actuation pressure is low, the high pressure oil supply circuit may have a leak.

   1. Unplug the injection actuation pressure control valve and the unit injector connectors.

   2. Disable the unit injectors with ET and/or the engine shutdown switch.

   3. Remove the valve mechanism covers.

   4. Crank the engine while you check the drain holes in the unit injector adapter and the jumper block seals for leaks.

   5. Repair any leaks and repeat Step 4.

   6. If the injection actuation pressure during cranking remains low, there may be a problem with the pump compensator displacement control. Replace the pump compensator control assembly and repeat Step 4.

Electrical Connectors

Check for correct installation of ECM connectors J1/P1 and J2/P2 and the unit injector connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".

Unit Injectors

1. Use ET to determine if there are any Active Diagnostic Codes for the unit injectors.

2. Perform the Injector Solenoid Test on ET in order to determine if all of the injector solenoids are being energized by the ECM.

3. Perform the Cylinder Cutout Test on ET in order to identify any misfiring cylinder(s). Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for more information.

Fuel Supply

1. Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.

2. Check the fuel tank for foreign objects which may block the fuel supply.

3. Check for air in the low pressure fuel supply system if any of the following procedures have been performed:
   • Replacement of the fuel filters

   • Service on the low pressure fuel supply circuit

   • Replacement of unit injectors

4. Purge air from the low pressure fuel supply circuit. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the complete procedure.

   Note: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.

5. Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Instruction, SEBD0717, "Diesel Fuels And Your Engine".

6. Check the fuel pressure during engine cranking. Check the fuel pressure after the fuel filter. Refer to Testing and Adjusting, "Fuel System" for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve.

Air Inlet and Exhaust System

1. Inspect the air filter for a restriction. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.

2. Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System".